A human baby is born with approximately 300 bones. As the child develops, some of these bones fuse together to form the 206 bones of the adult human skeleton. In fact, the newborn cranium has three infused plates at birth to allow the baby’s head to pass through the birth canal. The bones of the skull fuse together as the child ages.
Babies typically have more cartilage than adults, and much of the newborn skeleton is still cartilage at birth. Over time, this cartilage turns into bone by the process of ossification. Specialized cells called "osteoblasts" are responsible for making new bones and rebuilding damaged bones. For their skeletons to develop properly, babies require a tremendous amount of calcium, such as that found in breast milk and formula. A nursing mother often needs calcium supplements to prevent bone loss while breastfeeding.
Another interesting fact is that the patella or kneecap in newborns is made entirely of cartilage and does not completely ossify until the child is 3 to 5 years old. This is why crawling toddlers do not seem to experience knee pain or trauma as they move around on the floor. The skeletal system is responsible for providing protection for the internal organs, supporting the body and facilitating movement. The skeletal system works very closely with the muscular system to perform these duties.